Rod, as a TV weather forecaster I see your job as serving two functions:1)  Forecasting tomorrows weather 2) Educating the public as to what could be happening long term.  I have tried to educate myself by looking at the literature of what has occurred and what trends are occurring and thought you might find them interesting.

 

We often hear that global climate change is coming in the next 50 years, etc. I believe it has already arrived.  Look at the recent arctic ice levels (http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm )  Note that even now at the end of Nov. that we are at 20% lower levels of ice than the average even though there is no sunlight there now.  Climate scientists have predicted that an Arctic Ocean loosing a lot of ice would result in 2 changes: 1) Lack of ice will cause more sunlight to be absorbed on a dark surface rather than be reflected; this is a strong feedback mechanism 2) The jet stream would be affected; first, by delaying its advance southward starting in the fall/winter months and an earlier advance in the spring and, second the troughs and ridges would be longer lasting. As the Arctic loses its temperature difference from land and waters to the south, there is not the energy to create as strong a jet stream that will allow for more rapid changes. Therefore, the troughs and ridges in the path of the jet become more pronounced. As an example look at spring of this year in the Midwest where a long lived high pressure area led to temperature more than 30 degrees warmer than average in early March.  These temperatures dried out the soil, the high pressure prevented rain and a severe drought was the result.  At the same time the jet stream plunged all the way to Mexico in the West. It was cool and wet in the American Southwest. It snowed in northern Mexico. The jet stream became so deformed, it broke off forming a “closed” or “cutoff” low pressure area.  In mid-July this high pressure ridge shifted slightly west leading to a long dry spell in the NW and record level of fires in the West.  This year the Rocky Mountains, at the highest elevations, did not get their first snow until the third week of October and then only a dusting.  While growing up in this Rocky Mountain region 50 years ago the high elevations often got their first snow from mid-August to Labor Day.  Last year where the average was 45” of snow for the winter season only 4” fell, a new record low.  An omega block high pressure lasted over the area almost all winter.  Now the year before the blocking ridge was in the east and a trough in the West, resulted in record snowfalls. Both were extremely long lasting events.  As the climate warms further these snowfalls will be more likely to be rainfall.  Just a few days ago it was raining in Stanley, Idaho (elevation 7800 ft), usually the “icebox” location of the nation.  There is no snow cover there as of 12/03/2012.  Local residents say this has never occurred before.  Once again there is an “omega block” high pressure ridge over the Rockies.

 

In summary, we all know that water is slow to heat and equally slow to cool.  Once ice has melted, very much heat must be shed before it freezes again, especially freezing to a large depth. The Arctic Ocean melted much more quickly than predicted and all the efforts to curb greenhouse gases will not refreeze it, except over a period of hundreds of years. We are once again talking climate change, but now the climate has changed.  The high Arctic is much warmer on land and at sea than it used to be just a generation ago. Now, the Arctic Ocean will not refreeze except for a meaningless couple feet in late winter. Its deep blue waters will soak up more of the sun’s heat and make the Arctic warmer still.  Melting permafrost is releasing billions of tons of carbon dioxide and methane gas.  The normal daylight temperatures will raise slightly, but because of the 30 year running average the weather service provides, will not be obvious to most observers who get their weather from the television.  The rising night time low temperatures will be more obvious but not noted by the average lay weather watcher.

 

After writing this blurb I came across a recent article (see Dec 2012 Scientific American by Charles Greene pp 50-55) and the references cited therein.